Field of the Invention
The present invention concerns apparatus, i.e., test kit devices, for testing the acidity of lubricating oils dispersed in the working fluid of heating, ventilation, air conditioning and refrigeration (“HVACR”) systems, for example, the refrigerant of systems such as air conditioners, ice-making equipment, refrigerators, heat pump heating and cooling systems, and the like. The present invention also concerns methods of use of the aforesaid test kit devices.
HVACR systems employ Schrader valves to serve as access valves to inject refrigerant and/or oil into the system's refrigerant lines. The term “refrigerant lines” is used herein to refer to the working fluid transfer lines between the compressors and expansion units of HVACR systems. The Schrader valves may also be used to remove the contents of or samples from a system's refrigerant lines or to run tests on the lubricant oil for acid content. Each HVACR system typically has two Schrader valves, one located on the system high pressure side downstream of the compressor and upstream of the expansion unit, and the other on the system low pressure side downstream of the expansion unit and upstream of the compressor.
A Schrader valve consists of a machined valve body into which a valve core is threaded. The valve core is an assembly containing a spring, a movable core pin and a seating structure. The valve core is a service item that can be replaced and is suitably threaded for insertion into a refrigerant line access valve body to provide a normally closed valve arrangement. See Air Conditioning, Heating and Refrigeration Institute (formerly Air Conditioning and Refrigeration Institute) ARI Standard 720-97. The core pin in the access valve body can vary in its position depending on a number of variables including standard manufacturer recommended installation tolerances, wear and tear, and/or improper torques applied during valve core servicing. Every refrigerant system, small and large, contains at least one Schrader valve, which functions in a manner similar to the valve of an automobile tire. That is, depressing the core pin opens the valve to permit flow through the valve in either direction, depending on the respective pressures on either side of the valve.
Related Art
Refrigerant systems utilize lubricating oil which is mixed with the refrigerant fluid and thereby undergoes the same cyclic compression and expansion as the refrigerant. Generally, four different types or classes of lubricants are used in refrigerant systems. One class is mineral oil, another class is ester oil (which is based on the chemistry of polyol esters and is below referred to simply as “polyol ester oil”), the third class is polyalkaline glycol (PAG) oils and the fourth class is an alkylbenzene oil of the type commonly known as Zerol. The mineral oil is used for chlorofluorohydrocarbon (“CFC”) refrigerants such as those sold under the trademark FREON, and hydrochlorofluorocarbon (“HCFC”) refrigerants such as those designated R22. New refrigerants which are replacing CFCs and HCFCs are not soluble in mineral oil, so mineral oil is effectively being phased out along with the CFCs and HCFCs. Under the repeated compression and expansion cycles moisture or other impurities present in the system tend to chemically react with the lubricating oil to produce acidic reaction products. Even a very small amount of acid in the heat-transfer, e.g., refrigerant, system wreaks havoc on the system's equipment, most notably the system's compressor. Checking the system for acid is a routine maintenance procedure in large commercial air conditioning or refrigerant systems because, if detected early enough, acidic components can be economically removed from the system before the compressor or other parts of the system are irreparably damaged.
Title 40, Code of Federal Regulations (“CFR”), §608(c)(1), states that it is “unlawful for any person, in the course of maintaining, servicing, repairing or disposing of an appliance or industrial process refrigeration, to knowingly vent or otherwise knowingly release or dispose of any Class I or Class II substance used as a refrigerant in such appliance (or industrial process refrigeration) in a manner which permits such substance to enter the environment.” However, the U.S. Environmental Protection Agency has issued “applicability determinations” that clarify that releases of refrigerant associated with oil sampling and testing are allowable under 608(c)(1) provided the release is “(a) less than one half ounce (14 grams) and (b) the duration of the test procedure from beginning to end, does not last more than 5 seconds.”
The prior art discloses that litmus paper may be used in large systems to test the lubricant oil for acidity. However, litmus paper is not sensitive enough to provide a timely indication of low levels of acidic components present in the oil. By the time the litmus paper turns pinkish to indicate the presence of acid, the acid content is already high enough that the refrigerant system equipment has likely sustained significant damage. U.S. Pat. No. 6,514,765, issued Feb. 4, 2003 to Robert P. Scaringe et al., shows a hand-held test kit used to draw a refrigerant sample for testing and discloses the use of litmus paper and other acid color change papers positioned within the test kit. The color change papers are said to detect the presence of acids in the entrained oil of the refrigerant flowed over the color change paper.
The applicant's International Patent Publication WO 2012/166760 A1, published on 6 Dec. 2012 and entitled “Test Kit For Detecting Acids in Refrigerant Lubricating Oils and Method of Use” (“the '760 publication”) discloses a test kit designed to have refrigerant from the Schrader valve of a refrigerant system flowed through it by pressing the device upon a conventional Schrader valve to collect a lubricating oil sample, as shown in FIG. 3 and described in paragraph [0046] of the '760 publication. Filters 13a and 13b, as shown in FIGS. 1-1D, and a frangible ampoule 14 containing a liquid pH indicator 16 are interposed within tube 12, which is transparent or translucent. The tube 12 is flexible enough to be compressed sufficiently to rupture frangible ampoule 14 to release the liquid pH indicator without rupturing flexible tube 12. See paragraphs [0031] and [0044]. Alternatively, as illustrated in FIG. 4 of the '760 publication, the liquid pH indicator may be added from exteriorly of the test device 10′ by opening hinged end cap 18b′. 
A difficulty encountered with such prior art flow-through test kits is that of “blow-through”, that is, the pressure and velocity of the pressurized refrigerant is such that most of the entrained lubricating oil is carried out of the test kit with the refrigerant fluid, making it extremely difficult if not impossible to obtain even a small lubricating oil sample and to meet the sampling limitations of 40 CFR §608(c)(1). Prior art expedients include increasing the volume of the collection chamber of a test kit, introducing baffle means within the tube, extending the length of the tube and/or configuring the tube to provide a non-linear tortuous or baffled flow path. Insofar as the applicant is aware none of the known acid test kits adequately addresses the “blow-through” problem. In addition, some suffer from excessive cost and size. The test kit must be compact enough to be manipulated within the often limited confines of the refrigeration equipment.
Further, known test kits often require an oil sample size usually measured in multiple milliliters (“ml”), for example, 10 to 30 ml, approximately 10 to 30 grams. Withdrawing an amount of refrigerant to provide a lubricating oil sample of that size is technically feasible in large commercial refrigeration and air conditioning systems, even if not in compliance with 40 CFR §608(c)(1). However, taking such a large sample size is not feasible for smaller systems, such as small to medium capacity air conditioning units, household refrigerators, household and automotive air conditioning systems and the like.
Unless specifically otherwise stated or if the context clearly requires otherwise, as used herein and in the claims, the following terms shall have the indicated meanings whether used in singular or plural form.
The terms “lubricant” and “lubricating oil” are used interchangeably below and unless otherwise specified refer to the lubricating oil entrained in the refrigerant of a refrigeration system and to such lubricating oil collected as a sample within the test kit of the present invention.
The term “refrigerant” or “refrigerant fluid”, unless otherwise specified, means broadly any compressible fluid suitable for use in a refrigerant system.
The term “fluid” shall mean and include a gas or vapor, a liquid, and mixtures of a gas or vapor with a liquid, and unless so specified does not exclude the presence of lubricating oil entrained in the fluid.
The term “refrigerant system” shall mean and include conventional refrigerant systems, air conditioning systems, heat pump heating and cooling systems, ice making systems, systems for cooling equipment and reactor vessels, and comparable systems in which a refrigerant is alternately compressed and expanded.
The term “effective test liquid” shall mean and include a combination of a pH indicator, for example, a liquid pH indicator, and lubricating oil to form a test liquid of such composition and such size as to show a discernable color change at a preselected acid pH.
The term “sufficiently transparent”, as applied to the collection chamber of the test kit of the present invention, means fully transparent or translucent enough to enable observation of a discernable color change of the test liquid from exteriorly of the test kit.
A “flexible” or “collapsible” collection chamber, e.g., a tube, means a collection chamber which can be compressed, at least at a particular location thereof, sufficiently to crush an appropriately sized frangible ampoule disposed within the collection chamber, without rupturing the collection chamber or otherwise impairing the physical integrity of the collection chamber.
The term “disentrained” applied to lubricating oil means lubricating oil removed from the refrigerant or refrigerant fluid by flowing the refrigerant through the test kit of the present invention.